As will be discussed herein, the present process is applicable to any conjugate yarn that includes a polyamide as one of its components. The present process improves the absorption characteristics of fabrics of any construction (woven, knit, or nonwoven) that are comprised of microdenier yarns that result from splitting conjugate multi-component yarns. Microdenier fabrics are traditionally created by mechanically or chemically splitting a conjugate yarn into its elementary filaments. Although the benefits of this process are readily apparent on a specific nonwoven fabric that will be discussed in detail herein, it should be understood that it is equally applicable to woven or knitted microdenier fabrics created from splittable yarns.
Nonwovens are known in the industry as an alternative to traditional woven or knit fabrics. To create a nonwoven fabric, a fibrous web must be created and then consolidated. Staple fibers are formed into a web through the carding process, which can occur in either wet or dry conditions. Alternatively, continuous filaments, which are formed by extrusion, may be used in the formation of a web. The web is then consolidated and bonded by means of needle-punching, point-bonding, chemical bonding, or hydroentangling. A second bonding technique may also be employed.
A preferred substrate for the present disclosure is a nonwoven formed of continuous splittable filaments that are extruded as a web and then consolidated. The continuous conjugate filaments are obtained by means of a controlled spinning process. The continuous filaments have the following characteristics: (1) the continuous filaments are comprised of at least two elementary filaments and at least two different fiber types; (2) the continuous filaments are splittable along at least a plane of separation between elementary filaments of different fiber types; (3) the continuous filaments have a filament number (that is, titer or yarn count) of between 0.3 dTex and 10 dTex; and (4) the elementary filaments of the continuous filament have a filament number between 0.005 dTex and 2 dTex. Simply put, the nonwoven fabric can be described as a nonwoven fabric made from conjugate filaments. Such a fabric is described in U.S. Pat. Nos. 5,899,785 and 5,970,583, both to Groten et al., each of which is incorporated herein by reference.
A wide range of synthetic materials may be utilized to create the elementary filaments of the continuous conjugate filaments. The conjugate filaments used the present process differ from those common in the art in that they are comprised of elementary filaments of different polymer types. Such polymer types may include polyesters, polyamides, polyolefins, polyurethanes, and the like.
However, the present invention is intended to improve the characteristics of fabrics that contain polyesters or polyamides as part of the conjugate yarns. As such, the group of polymer materials forming the elementary filaments is selected from among the following groups: polyester and polyamide; polyolefin and polyamide; polyurethane and polyamide; polylactic acid and polyamide; polyester, polyolefin, and polyamide; and polyester, polyolefin, polyurethane, and polyamide; or any other combination as may be known in the art.
It is desirable in the nonwoven fabrics described above to fully split, or separate, the elementary filaments of the continuous filaments from one another. The same goal applies to woven or knitted fabrics as well. The resultant microdenier strands contribute to the textile quality of the nonwoven fabric. The microdenier yarns contribute to the softness and hand of woven or knitted fabrics.
However, the fabric described in the above-referenced patents is not as absorbent as many other synthetic fabrics that may be used in the drying or wiping cloth market and that may have a similar composition but different construction. The nonwoven of the present disclosure is more absorbent after being subjected to the present process.